rewrote the tests for assert_error_match()
rewrote the tests for assert_error_match()

Make the tests more robust in that way they check for the correct
case of failing.
Additionally some white space and newline cleanups.

Signed-off-by: Michael Roth <b63e24eec55b9c8de46eeea2193ca36823bfc515@nessie.de>

ennorehling/lunit,sam-github/lunit,shmul/lunit